Wrack Seaweed.

Wrack Seaweed.

Observation - Wrack Seaweed. - UK and Ireland. Description: Dark green seaweed firmly attached to rocks on the edge of the muddy shore. Flat fronds with a centr

Dark green seaweed firmly attached to rocks on the edge of the muddy shore. Flat fronds with a central rib terminating in fork like air bladders. Fronds approx 25-25cm.
I think it might be Fucus spirals.